Hangovers are the result of drinking excessive alcohol. However, the amount of alcohol required to produce a hangover varies from person to person. For example, in some people, a single alcoholic drink is sufficient to trigger a hangover. The symptoms of a hangover can include nausea and vomiting, headache and muscle ache, dry mouth, fatigue and weakness, shakiness, decreased ability to concentrate, reduced sleep quality or duration, mood disturbances, thirst, and rapid heartbeat. These symptoms often arise as one's blood alcohol level returns to normal levels after an episode of drinking. If an episode of drinking occurs in the evening, the hangover symptoms typically appear the following morning.
Multiple factors can contribute to the development of a hangover. For example, alcohol has a diuretic effect that causes excess urination leading to dehydration. Dehydration in turn causes lightheadedness, dizziness, and thirst. Alcohol also irritates the stomach lining by increasing the production of acid and by delaying gastric emptying. These effects can cause nausea, vomiting, and abdominal pain. Alcoholic beverages contain substances called congeners, which can contribute to hangover symptoms. Alcohol also reduces blood sugar levels, which can cause weakness, fatigue, mood disturbances, and unsteadiness.
Hangover has generally been considered to be an insolvable problem, and there are currently no truly effective cures for hangover. It is generally believed that the only way to reliably avoid symptoms is to abstain from drinking alcohol. Thus, there has been a long-felt need for an effective solution to the problem of hangover.